The major benefits from the core are: 1) creation of a repository for all the expression plasmids needed to tag proteins for pull down-based protein isolation procedures and for validating putative binding interactions; 2) provision of shuttle vectors needed to produce lentivirus; 3) provision of state of the art, well characterized lentivirus vectors to qualified investigators. Lentivirus vectors have proved exceptionally useful in providing efficient transduction of quiescent brain cells that have been traditionally resistant to retroviral-mediated transduction. Recombinant lentiviruses do not encode viral proteins and have the benefit of low toxicity and immunogenicity and produce stable proviral integrants. 4) provision of protocols for isolating tagged proteins.